VMware: Ethernet Adapters

All of our VMs are running on eithre flexible or E1000 ethernet adapters. Is there a benefit in switching to VMXNET adapters? Will we see any performance benefits or is it unnoticable?
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Andrew Hancock (VMware vExpert / EE MVE^2)VMware and Virtualization ConsultantCommented:
Performance will increase, as the VMXNET3 is a 10GBe network interface, compared to the legacty E1000. Also E1000 provides additional overhead on the VM (hypervisor CPU). VMXNET is truly virtualised.

The E1000 should only be used for installation of an OS, because VMXNET3 is not included with the OS.

VMware Tools needs to be installed to support VMXNET3.

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I would recommend VMXNET3 as well. It will increase overall performace.

You can refer to VMware KB for more info

Choosing a network adapter for your virtual machine (1001805)

Hope this helps.
pzozulkaAuthor Commented:
I read that when VMs talk to each other on the same host they don't use the physical network. Our physical network is 1GB and the physical NICs on the ESXi hosts are 1GB.

Having said that:

1) Will VMs running VMXNET3 see any performance gain when communicating with VMs on other hosts? Why/How?

2) Will VMs running VMXNET3 communicate with other VMs on same host with same network adapter at 10GB?
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1) Yes, usually you will see equal or greater performance gain on VMXNET3 vs E1000.  Vmware designed VMXNET3 to support high performance and from scratch

You can read this for detail.
Performance Evaluation of VMXNET3 Virtual Network Device

2) If VMs are running on the same host and connect to the same vSwitch network, they can communicate at higher throughput then 1GB or more.  It depends on how fast the VM can push the network traffics to each other and the hardware configurations (mainly CPU) for the vSphere host.

Hope above helps.
Andrew Hancock (VMware vExpert / EE MVE^2)VMware and Virtualization ConsultantCommented:
1. Yes, it's a better network interface.

2. Yes.

if you are currently happy with your chosen solution, do not change it.
pzozulkaAuthor Commented:
I think this is also a great link for any future purposes. Compares legacy NIC (e1000) to VMXNET:

pzozulkaAuthor Commented:
After reading the suggested material and learning more about the differences, here are my conlcusions.

Please correct me if I'm wrong.

1. If our underlying physical network is only 1Gb, using VMXNET3 will not make traffic between VMs and physical servers go any faster than the physical limit of 1Gb.

2. If our underlying physical network is only 1Gb,
VMs running older OS -- Windows XP or Windows Server 2003 will only see marginal improvements. In our environment a Windows XP VM use to show 1.0 Gbps in the XP taskbar, and now shows 1.4 Gbps on the new VMXNET3 adapter.
VMs running newer OS -- Windows 2008 and up offer support for parallelism by allowing network processing on different cores simultaneously so networking throughput between VMs on same host will be limited by the processor speed and its ability to handle high volume network processing tasks. So we should see higher network performance improvement on VMs with newer OS. Communication with VMs on other hosts, or other physical machines will be limited by the Gigabit NIC of the ESXi host.
Andrew Hancock (VMware vExpert / EE MVE^2)VMware and Virtualization ConsultantCommented:
We can only advise and recommend if you have time in the future to alter machines to use vmxnet3

Any new machines we would recommend you use vmxnet3.
I find issues with using VMXNET3 if your physical network is 1 Gbps and having mixed older OS's.
I recommend sticking to  E1000 interfaces until your physical network infrastructure catches up.
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